The present invention is related to manhole and gate valve construction and, more specifically, to sealing structures for gate valves that prevent or substantially limit infiltration of liquids into the manhole or gate valve area.
Improvements have been made to gate valve sealing structures for added stability and improved sealing capabilities. Examples of such improvements can be seen in Gagas, U.S. Pat. Nos. 6,226,929 and 6,044,590 and Warnes, et al., U.S. Pat. No. 6,354,325. While these improvements have advanced the art, there is further room for improvement within the art.
The gate valve boxes that these sealing structures cooperate with generally are cast iron devices. Consequently, individual boxes may have imperfections that the sealing structures need to adapt to when being placed on the boxes. Sealing structures have been made out of flexible materials, such as rubber.
One disadvantage of currently made and designed sealing structures is a loss of tight sealing ability when providing a flexible structure. Because sealing structures are used in rigorous environments that do not provide a worker with much space when installing the sealing structures, such flexible structures can lead to deficient sealing arrangements.
Sealing structures have been designed with internal fingers or extensions that are used to center the sealing structure on a gate valve box. While effective for centering the sealing structure, such structures also leave room for improvement for complete sealing around the gate valve. Also, such structures do not assist in fitting a pipe, or properly acting as a pipefitter, to the sealing structure and gate valve box.
These structures and other prior art structures have a straight cylindrical arrangement that conforms to the size of the pipe. While the sealing structures are designed to tightly fit around or over the pipes, such a design also makes it hard to secure the pipe properly in place. The pressure or force between the pipe and the sealing structure increases as the pipe is mated with the structure, which leads to a difficult process for the installer and increases potential injury for the installer. It would be advantageous to have a sealing structure that would provide a tight sealing structure that would ease the installation process as related to current sealing structures.